Reciprocating cutting tool and method

ABSTRACT

A reciprocating cutting tool includes a shank for mounting in a pneumatic hammer, a blade holder assembly connected to the shank and a blade clamped in the blade holder assembly. The blade holder assembly includes a base member and a retainer member which are clamped together. A blade receiver is formed between the base and retainer members. The base member includes a recess and the retainer member includes a shoulder which is received in the base member recess for abutment by a fixed end of the blade. A method of removing adhesively-attached ornamentation from a vehicle body panel includes the steps of providing a blade holder assembly with base and retainer members, providing a blade with a proximate end and a distal end having a sharpened distal cutting edge, clamping the base and retainer members together with the blade proximate end therebetween, providing the retainer member with a shoulder, abutting the blade proximate end against the shoulder, reciprocating the blade holder assembly and advancing the blade cutting edge through adhesive between the ornamentation and the vehicle body panel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to reciprocating cutting toolsand methods, and more specifically to a reciprocating cutting tool and areciprocating cutting method which are particularly well adapted forremoving molding and emblems from vehicle body panels.

2. Description of the Prior Art

Cutting tools of different sizes and configurations have heretofore beendevised to meet the requirements of various material cuttingapplications. Tools with reciprocating cutting actions typically havecutting edges along their side edges or leading edges and include avariety of chisels, saws, knives, scrapers, etc. Hand tools forreciprocative cutting include chisels, scrapers and various hand saws.Power tools for reciprocative cutting include motors for reciprocatingvarious tool attachments, and can utilize various power sources such aselectricity, compressed air, etc.

One type of reciprocating power tool which is commercially availablecomprises a pneumatic or air hammer. Air hammers are commonly used inthe repair of vehicle bodies, with tool attachments such as chisels,punches and the like attached thereto. Vehicle repair facilities arecommonly equipped with air compressors for powering air hammers andother pneumatic tools.

In repairing and replacing damaged vehicle body panels, it is oftenpreferable to remove therefrom existing ornamentation (e.g., molding andemblems) to facilitate painting the new or repaired body panels.Otherwise, paint might tend to collect between the ornamentation and thebody panels, which could be aesthetically undesirable. Such vehicleornamentation is sometimes attached to the vehicle body panels bymechanical fasteners such as screws, but the holes for such mechanicalfasteners can facilitate the onset of rust and corrosion in the bodypanels which are penetrated thereby. Therefore, a preferred method forattaching molding and emblems is with adhesive, which is preferablylocated at or near the peripheral edges of the ornamentation to preventwater from collecting therebehind.

Removing such ornamentation can involve cutting one or more beads ofadhesive. One method of removing molding and emblems involves pryingthem loose from the vehicle body panels. However, molding and emblemspried loose from vehicles are susceptible to damage in the process. Forexample, vehicle body moldings often include strips of reinforcingmaterial such as metal, which are susceptible to bending when removedfrom the vehicle body panel. Cutting wires have also been utilized forornamentation removal. However, they often require two workers and canbe relatively slow.

It is generally desirable to preserve the molding and emblems as intactas possible for reinstallation to minimize material costs. However, themolding and emblems must be removed relatively quickly to avoidincurring undue labor costs.

Heretofore, there has not been available a reciprocating cutting tooland method with the advantages and features of the present invention.The present invention addresses some of the shortcomings anddisadvantages of previous tools and procedures as noted above.

SUMMARY OF THE INVENTION

In the practice of the present invention, a reciprocating cutting toolis provided which includes a shank for mounting on a power tool, forexample, an air hammer. A blade holder assembly is mounted on the shankand includes a base member and a retainer member. The retainer memberhas a shoulder which is received in a recess formed in the base member.The base and retainer members are clamped together, e.g., by mechanicalfasteners, and form a blade receiver therebetween which terminates atthe retainer member shoulder. A blade includes a fixed, proximate endwhich is clamped between the base and retainer members in the bladereceiver in abutment with the shoulder and a distal end with a cuttingedge. In the practice of the method of the present invention, moldingand emblems are removed from vehicle body panels by reciprocating acutting tool. The method includes the steps of providing base andretainer members, clamping a blade therebetween, providing a distalcutting edge on the blade and guiding the tool between a vehicle bodypanel and ornamentation adhesively mounted thereon. The tool isreciprocated automatically and its cutting edge separates an adhesivebead securing the molding or the emblem to the vehicle body panel.

OBJECTS AND ADVANTAGES OF THE INVENTION

The principal objects and advantages of the present invention include:providing a reciprocating cutting tool; providing such a tool with ashank, a blade holder assembly and a blade; providing such a toolwherein the blade holder assembly is relatively heavy in relation to theblade; providing such a tool wherein the blade is securely retained inplace by the blade holder assembly; providing such a tool which includesa shoulder for abutment by a fixed end of the blade; providing such atool with a replaceable blade; providing such a tool which isparticularly well adapted for removing ornamentation such as molding andemblems from vehicle body panels; providing such a tool which is adaptedfor use in connection with commercially available air hammers; providingsuch a tool which is economical to manufacture, efficient in operationand capable of a long operating life; providing a reciprocating cuttingmethod; providing such a method which is particularly well adapted forremoving ornamentation such as emblems and molding from vehicles;providing such a method which tends to be relatively efficient;providing such a method which can be practiced with air hammers whichare commercially available; providing such a method which utilizes areciprocating cutting tool with a replaceable blade; and providing sucha method which can be adapted to various vehicle body styles forremoving molding and emblems therefrom.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a reciprocating cutting tool embodyingthe present invention, shown mounted in a pneumatic hammer and in theprocess of removing molding from a vehicle body panel in accordance witha method of the present invention.

FIG. 2 is an enlarged, fragmentary, cross-sectional view of thereciprocating cutting tool, taken generally along line 2--2 in FIG. 1.

FIG. 3 is a top plan view of the reciprocating cutting tool, withportions broken away to reveal internal construction.

FIG. 4 is a fragmentary, distal end elevational view of thereciprocating cutting tool taken generally along line 4--4 in FIG. 3.

FIG. 5 is an enlarged, fragmentary, cross-sectional view of thereciprocating cutting tool, taken generally along line 5--5 in FIG. 3.

FIG. 6 is an enlarged, cross-sectional view taken generally along line6--6 in FIG. 1 and particularly showing molding adhesively attached tothe vehicle body panel.

FIG. 7 is a fragmentary, top plan view of a reciprocating cutting toolcomprising a first modified or alternative embodiment of the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS I. Introduction andEnvironment

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

Certain terminology will be used in the following description forconvenience in reference only and will not be limiting. For example, thewords "upwardly", "downwardly", "rightwardly" and "leftwardly" willrefer to directions in the drawings to which reference is made. Thewords "inwardly" and "outwardly" will refer to directions toward andaway from, respectively, the geometric center of the embodiment beingdescribed and designated parts thereof. Said terminology will includethe words specifically mentioned, derivatives thereof and words of asimilar import.

Referring to the drawings in more detail, the reference numeral 10generally designates a reciprocating cutting tool, shown operablyinserted into a pneumatic hammer 12. The pneumatic hammer 12 can be ahand-held type which is adapted for connection to a compressed airsource (not shown) by an air inlet hose 14. The pneumatic hammer 12includes a helical spring 16 for interchangeably retaining tools.Pneumatic hammers such as that shown at 12 are commercially availableand operate by reciprocating tools inserted thereinto, for example atoperating speeds of 1,000 cycles per minute or more.

Without limitation on the generality of useful applications of the tool10, it is shown removing a length of molding 18 from a vehicle bodypanel 20. The molding 18 has embedded therein a longitudinally-extendingreinforcing strip 22 which can comprise a material such as aluminum forincreasing the rigidity of the molding 18. The molding 18 can beattached to the vehicle body panel 20 by a pair of adhesive beads 24.

As shown in FIG. 6, a slight molding gap 26 can be formed between themolding 18 and the body panel 20, with the adhesive beads 24 fillingportions thereof.

The tool 10 generally comprises a shank 31, a blade holder assembly 32and a blade 33.

II. Shank 31

The shank 31 is generally cylindrical with proximate and distal ends 34,36. The shank proximate end 34 is adapted to be inserted into thepneumatic hammer 12 and includes an annular retainer flange 38 forsecuring the shank 31 in the pneumatic hammer 12 by means of the spring16.

The shank distal end 36 includes upper and lower portions 40, 42 whichcan be flattened and which converge distally. The shank distal end lowerportion 42 can generally lie in a plane which intersects at an acuteangle the longitudinal axis of the shank 31. The shank distal end upperportion 40, on the other hand, can generally lie in a plane which isapproximately parallel to the longitudinal axis of the shank 31.

Reciprocating cutting tools 10 which embody the present invention can beprovided with shanks of various lengths.

III. Blade Holder Assembly 32

The blade holder assembly 32 extends generally transversely with respectto the shank 31 and generally forms the configuration of a "T"therewith. The blade holder assembly 32 includes first and second ends44, 46.

The blade holder assembly 32 includes a base member 48 with inner andouter faces 50, 52 and leading and trailing edges 54, 56. The basemember outer face 52 includes a proximate portion 58 which is generallyparallel to the inner face 50 and a distal portion 60 which convergesfrom the proximate portion 58 towards the base member leading edge 54.The base member outer face portions 58, 60 generally form an obtusedihedral angle with respect to each other. A base member recess 62extends between the blade holder assembly ends 44, 46 and is open at thebase member inner face 50 and at its trailing edge 56.

A retainer member 68 includes inner and outer faces 70, 72 and leadingand trailing edges 74, 76. The retainer member 68 includes blade stopmeans comprising a shoulder 78 which projects from the retainer memberinner face 70 in proximity to the retainer member trailing edge 76. Theshoulder 78 extends between the blade holder assembly ends 44, 46.

The shoulder 78 includes an abutment face 80 which extendsperpendicularly between the member inner faces 50 and an offset face 82which is offset from (i.e., below) and generally parallel to theretainer member inner face 70.

The blade holder assembly 32 includes fastening means comprising aplurality (e.g., four are shown) of screws 84 with male-threaded shanks86 and heads 88 with hexagonal, closed-end bores 90 for drivingengagement with an Allen wrench. The blade holder assembly 32 includes acorresponding plurality of screw receivers 92 each including: afemale-threaded, closed-end base portion 94 open at the base memberinner face 50; a smooth bore retainer portion 96 open at the retainermember inner face 70; and a counterbore portion 98 open at the retainermember outer face 72.

A base cushion strip or pad 100 can be attached to the proximate portion58 of the base member outer face 52. The cushion strip 100 can comprise,for example, a resilient, non-scratching material such as foam rubber orfabric which can be held in place adhesively.

A blade end receiver 102 is formed between the member inner faces 50 andincludes a closed, proximate end 103 at the shoulder abutment face 80and an open, distal end 107. The blade end receiver 102 is penetrated bythe screw shanks 86.

The shank 31 is attached to the blade holder assembly 32, for example,by welding the shank distal end 42 on top of the retainer member outerface 72 approximately midway between the blade holder assembly ends 44,46 with a weldment 112 formed between the shank distal end 36 and theretainer member 68. Due to the angular orientation of the shank distalend lower portion 42 with respect to the shank longitudinal axis, theblade 33 lies generally in a plane with a corresponding angular orskewed orientation with respect to the longitudinal axis of the shank31. However, the tool 10 can be constructed with such angularorientations in a relatively wide range of suitable angles, or with theblade 33 substantially coplanar with the longitudinal axis of the shank31.

IV. Blade 33

The blade 33 can comprise a suitable flexible spring tool steel withmemory properties for returning the blade 33 to its original, generallyplanar configuration when not subjected to a bending load. Other desiredcharacteristics of the blade 33 include hardness for holding a cuttingedge 108 and a relatively smooth finish on the surfaces of the blade 33to avoid or at least reduce the possibility of damage to the finish ofthe vehicle body panel 20.

The blade 33 includes a proximate fixed end 104 with a proximate edge105 and a plurality of blade fastener receivers 106 corresponding to thelocations of the screw receivers 92 in the blade holder assembly 32. Theblade 33 includes a distal free end 109 with a distal cutting edge 108which can be sharpened and can have a distally-convex, curvedconfiguration (FIGS. 1 and 3). The blade 33 includes a pair of generallyparallel side edges 110 which are spaced apart a distance slightly lessthan a width of the blade holder assembly 32 between its ends 44, 46.

The blade 33 is mounted in the blade holder assembly 32 by placing itsfixed end 104 in the blade receiver 102 with the blade proximate edge105 preferably in abutment with the shoulder abutment face 80. Thescrews 84 extend through the screw receivers 92 and the blade fastenerreceivers 106 whereby the base and retainer members 48, 68 can beclamped tightly together with their inner faces 50, 70 in clampingengagement on the blade proximate end 104.

The blade distal cutting edge 108 can be formed by honing one face(e.g., the outer face which is engaged by the retainer member 68) of theblade 33 to a relatively sharp convergence with the other face of theblade 33. Spring tool steel with a thickness of about 0.012 inches hasbeen found to be suitable for the blade 33. The honed cutting edge 108can have a width of about 0.0625 inches whereby an included dihedralangle in the range of about 10° to 12° is formed between the cuttingedge 108 and the other face of the blade 33.

After honing the cutting edge 108, it has been found to be preferable topolish the cutting edge 108 with a suitable, very fine abrasive, such assandpaper with number 2000 grit. The cutting edge 108 thus has a degreeof sharpness which facilitates separation of the adhesive beads 24,while protecting the finish on the vehicle body panel 20 from damagewhich could occur if the cutting edge 108 were not polished in thismanner.

V. Reciprocating Cutting Method

A reciprocating cutting method in accordance with the present inventionis disclosed which utilizes the cutting tool 10. The method is disclosedin connection with a procedure for removing the molding 18 from avehicle body panel 20, but could be practiced in a variety of otheruseful procedures.

The reciprocating cutting method includes the steps of mounting thecutting tool 10 in the pneumatic hammer 12 and actuating the hammer 12,i.e., by communicating a source of pressurized air therewith.

The cutting edge of the blade 33 separates the adhesive beads 24,allowing the tool 10 to advance. The tool 10 can generally slide betweenthe separated molding 18 and the vehicle body side panel 20 with theshank 31 generally sliding along one side of the molding 18. In thisfashion the tool 10 can be advanced along the entire length of themolding 18 for removing same. The cushion strip 100 protects the finishof the vehicle body panel 20 as the tool 10 slides therealong.

Although the tool 10 can be used in various ways, each adapted to theconfiguration and position of a piece of ornamentation being removed, apreferred method of use involves advancing the tool 10 in a directiongenerally transverse to a longitudinal axis of the molding 18 whereby asection of the molding 18 roughly corresponding to the width of theblade 33 is separated from the body panel 20 on each pass of the tool10. The tool 10 can thus be advanced along the length of the molding 18in successive cutting swaths. This transverse cutting procedure can bepracticed by inserting the blade 33 from either side of the molding 18,depending upon the position and orientation of the body panel 20 and thecharacteristics of the molding 18. For example, if difficulty isencountered in inserting the blade 33 from one side of the molding 18due to damage or some other cause, it may be possible to insert theblade 33 from the other side or from an end of the molding 18. Since awide variety of ornamentation configurations and positions may beencountered, a correspondingly wide variety of techniques and proceduresmay be practiced with the tool 10 to perform particular cuttingprocedures.

For certain applications of the method described above, the procedurecan be facilitated by applying a suitable lubricant 114 to the blade 33,particularly along its distal cutting edge 108, and to the edges of themolding 18 adjacent to the adhesive beads 24. The lubricant 114 cancomprise, for example, a soap-like material, such as a type of materialwhich is commonly used in vehicle body shops for coating and maskingparts, or some other suitable lubricant for reducing friction on theblade 33 as it passes through the adhesive beads 24.

With the base and retainer members 48, 68 tightly clamped together bythe screws 84, the blade proximate edge 105 preferably abuts theshoulder abutment face 80. The blade holder assembly 32 preferably has asignificantly greater mass than the blade 33. The momentum of the bladeholder assembly 32 as it is reciprocated by the pneumatic hammer 12 cantransmit substantial cutting and thrusting force to the blade 33. Thegreatest forces are anticipated to be compressive forces during thruststrokes as the tool 10 advances through the adhesive beads 24. Theimpacts of such compressive forces are transferred from the blade 33directly into the shoulder 78 for resistance and absorption by theentire mass of the blade holder assembly 32. It is anticipated that atleast partly because of this direct, abutment-contact,force-transmitting feature of the tool 10, there is little tendency forthe screws 84 to loosen or for the blade holder assembly 32 to releaseits clamping engagement grip on the blade 33. It is also anticipatedthat this feature of having the force applied directly to the shoulder78 can considerably prolong the useful life of the tool 10 in operation.

Other vehicle ornamentation, such as emblems and the like, can beremoved from the body panel 20 by following a similar procedureaccording to the method of the present invention.

VI. First Alternative or Modified Embodiment Reciprocating Cutting Tool120

FIG. 7 shows a cutting tool 120 comprising a first modified oralternative embodiment of the present invention. For vehicleornamentation removal applications, the configuration of the modifiedcutting tool 120 is generally preferred over that of the cutting tool 10described above, but such preferences may vary among different users andamong different ornamentation-removal task conditions.

The cutting tool 120 is substantially identical to the cutting tool 10described above, except for a blade 122 with a modified configuration.The blade 122 includes a distal end 124 with a relatively straightcutting edge 126 whereby the blade 122 has a substantially rectangularconfiguration with rounded distal corners 128.

The modified or alternative embodiment reciprocating cutting tool 120can function in a manner substantially similar to the reciprocatingcutting tool 10 in accordance with the method of the present invention.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed and desired to be secured by Letters Patent is asfollows:
 1. A blade holder for mounting a blade with a fixed end to ashank, which comprises:a base member; a retainer member; mounting meansfor mounting said retainer member on said base member; a blade fixed endreceiver formed between said base member and said retainer member; stopmeans associated with said base member and said retainer member forengaging the blade fixed end, said stop means comprising a shoulderformed on said base member and a recess formed in said retainer member,the shoulder being received in the recess; and shank mounting means formounting the shank on said base member.
 2. The blade holder as set forthin claim 1, which includes:said base member having an inner face withsaid recess open thereat; said retainer member having an inner face withsaid shoulder projecting therefrom; and said blade fixed end receiverbeing formed between said base and retainer member inner faces.
 3. Theblade holder as set forth in claim 2 wherein said mounting meanscomprises a mechanical fastener.
 4. The blade holder as set forth inclaim 3, which includes:a fastener receiver comprising a female-threadedbase member portion located in said base member and open at said basemember inner face and a retainer member portion extending through saidretainer member and open at said retainer member inner face; and saidfastener comprising a screw rotatably received in said receiver retainermember portion and threadably received in said receiver base memberportion.
 5. The blade holder as set forth in claim 1, whichincludes:said base member having a leading edge, a trailing edge, aninner face and an outer face; and said base member outer face having asloping configuration converging toward said base member inner face at areduced thickness area adjacent to said base member leading edge from amaximum thickness area adjacent to said base member trailing edge. 6.The blade holder as set forth in claim 1, which includes:cushion meansmounted on said base member.
 7. A reciprocating cutting tool, whichcomprises:an elongated shank having a longitudinal axis and a proximateend and a distal end having a flattened portion; a blade holder assemblyincluding:a base member with a base member inner and outer faces, basemember leading and trailing edges and a recess open at said base memberinner face and at said base member trailing edge; a retainer member withretainer member inner and outer faces, retainer member leading andtrailing edges and a shoulder projecting from the retainer member innerface and received in the base member recess; blade holder fastener meansfor fastening the base and retainer members together, the shankflattened portion generally lying in a plane which forms an acute anglewith respect to the shank longitudinal axis; shank mounting meanscomprising a weldment securing said flattened portion to the outer faceof the retainer member for mounting the shank to the retainer member; ablade fixed end receiver formed between said base member inner face andsaid retainer member inner face, said blade fixed end receiver having aproximate end closed by said shoulder and an open, distal end; and ablade including a fixed proximate end, a free distal end and a cuttingedge formed on said distal end, said fixed proximate end of the bladebeing received in said blade fixed end receiver.
 8. The tool as setforth in claim 7 wherein:said blade holder assembly includes first andsecond opposite ends; and said base member recess and said retainermember should extend between said blade holder assembly opposite ends.9. The tool as set forth in claim 7, which includes:a fastener receiverincluding a female-threaded base member portion located in said basemember and open at said base member inner face and a retainer memberportion extending through said retainer member and open at retainermember inner face; and a screw rotatably received in said receiverretainer member portion and threadably received in said receiver basemember portion.
 10. The tool as set forth in claim 7 wherein:said bladecutting edge has a curved, distally-convex configuration.
 11. The toolas set forth in claim 7 wherein:said blade cutting edge has a generallystraight configuration.
 12. The tool as set forth in claim 7, whichincludes:cushion means mounted on said base member outer face.
 13. Thetool as set forth in claim 7, which includes:said base member outer facehaving a sloping configuration converging toward said base member innerface at a reduced thickness area adjacent to said base member leadingedge from a maximum thickness area adjacent to said base member trailingedge.
 14. The tool as set forth in claim 7 wherein:said blade isgenerally planar, and is made of flexible spring tool steel having theproperty for returning to its original, generally planar configurationwhen not subjected to a bending load.
 15. The tool as set forth in claim14 herein said blade is made of spring tool steel with a thickness ofabout 0.012 inches and having a honed cutting edge with a width of about0.0625 inches whereby an inclined angle in the range of about 10° to 12°is formed between the cutting edge and a face of the planar blade.
 16. Areciprocating tool, which comprises:a shank with proximate and distalends; a blade holder assembly including:a base member with base memberinner and outer faces, base member leading and trailing edges and arecess open at said base member inner face and at said base membertrailing edge; a retainer member with retainer member inner and outerfaces, retainer member leading and trailing edges and shoulderprojecting from the retaining member inner face and received in the basemember recess; and blade holder fastener means for fastening the baseand retainer members together; shank mounting means for mounting theshank to the retainer member; a blade fixed end receiver formed betweensaid base member inner face and said retainer member inner face, saidblade fixed end receiver having a proximate end closed by said shoulderand an open distal end; and a blade including a fixed proximate end, afree distal end and a cutting edge formed on said distal end, said fixedend being received in said blade fixed end receiver, said base memberouter face having a sloping configuration converging toward said basemember inner face at a reduced thickness area adjacent to said basemember leading edge from a maximum thickness area adjacent to said basemember trailing edge.
 17. A reciprocating tool, which comprises:a shankwith proximate and distal ends; a blade holder assembly including:a basemember with base member inner and outer faces, base member leading andtrailing edges and a recess open at said base member inner face and atsaid base member trailing edge; a retainer member with retainer memberinner and outer faces, retainer member leading and trailing edges andshoulder projecting from the retaining member inner face and received inthe base member recess; and blade holder fastener means for fasteningthe base and retainer members together; shank mounting means formounting the shank to the retainer member; a blade fixed end receiverformed between said base member inner face and said retainer memberinner face, said blade fixed end receiver having a proximate end closedby said shoulder and an open distal end; and a blade including a fixedproximate end, a free distal end and a cutting edge formed on saiddistal end, said fixed end being received in said blade fixed endreceiver; and cushion means mounted on said base member outer face. 18.A reciprocating cutting tool, which comprises:a shank with a proximateend, a distal end, a longitudinal axis, and an annular retainer flangepositioned in proximity to said shank proximate end; said shank distalend including a lower, flattened portion generally lying in a planewhich forms an acute angle with respect to the shank longitudinal axis;a blade holder assembly including:first and second opposite ends; a basemember with base member inner and outer faces, base member leading andtrailing edges and a recess open at said base member inner face and atsaid base member trailing edge, said recess extending between said bladeholder assembly ends; a retainer member with retainer member inner andouter faces, retainer member leading and trailing edges and a shoulderprojecting from the retainer member inner face and received in the basemember recess, said shoulder extending between said blade holderassembly ends; a plurality of fastener receivers each having afemale-threaded base member portion located in said base member and openat said base member inner face and a retainer member portion extendingthrough said retainer member and open at said retainer member inner andouter faces; a plurality of screws each received in a respectivefastener receiver, each said screw being rotatably received in arespective receiver retainer member portion and threadably received in arespective receiver base member portion; a blade fixed end receiverformed between said base member inner face and said retainer memberinner face, said blade fixed end receiver having a proximate end closedby said shoulder and an open, distal end; said base member outer facehaving a sloping configuration converging toward said base member innerface at a reduced thickness area adjacent to said base member leadingedge from a maximum thickness area adjacent to said base member trailingedge; and cushion means mounted on said base member outer face; and ablade including a fixed proximate end with a proximate edge, a freedistal end, a distal cutting edge formed on said distal end and aplurality of blade fastener receivers in said blade fixed proximate endeach receiving a respective screw, said blade proximate end beingclamped between said member inner faces with said proximate edge thereofin abutment with said shoulder.